1. Field of the Invention
The present invention relates to a linear actuator.
2. The Prior Art
Initially, it is observed that a distinction is made between lifting columns for beds and lifting columns for height-adjustable tables. Lifting columns for beds are much more sturdy than lifting columns for tables, where the design of the latter is moreover an important parameter, because the lifting columns serve as table legs and thereby have a considerable influence on the appearance of the table. In order to be as free as possible in the design, drive units are desired which may be used in an arbitrary table leg directly or with just insignificant adaptations. This also means that the drive unit is slender and altogether takes up as little space as possible and may additionally be used for lifting columns with two extensible members
The invention is directed to lifting columns for height-adjustable tables, for which a variety of linear actuators are now available. All of these are largely based on spindle technique, viz. a hollow spindle in cooperation with a solid spindle. An example of this may be found in e.g. WO 02/39848 to Linak A/S and WO 01/78556 to Okin Gesellschaft für Antriebstechnik GmbH & Co. KG. WO 03/003876 A1 discloses an individual example of a linear actuator based on a chain which is driven by an electric motor via a transmission. A rod is secured to each of the runs of the chain between two pairs of chain wheels, said rod being extended from its respective end of the actuator. Although the structure appears as an elongated rod, it is still rather bulky, all things considered.
The object of the invention is to provide a new structure of a linear actuator.